1. Field of the Invention
This invention relates to a vehicle air-conditioning system capable of independently controlling left and right outlet air temperatures by adjusting flow proportions of warm and cool air flows, and particularly to a system capable of independently controlling the cooling of both left and right side occupants at times of maximum cooling by controlling a left-right air flow distribution.
2. Description of the Related Art
In conventional air-mixing type vehicle air-conditioning systems, an air-mixing door is operated at times of maximum cooling to a position in which it fully opens a cool air bypass passage and fully closes an air inflow path to a heat exchanger for heating. When there is an unbalanced incidence of solar radiation on a vehicle, such as when a passenger seat side (left side), is exposed to solar radiation while a driver seat side (right side) is not, a temperature difference due to the radiation arises between the two sides. Consequently, the amount of cooling necessary to achieve a comfortable temperature on the left side varies greatly with respect to the amount of cooling for the right side.
However, in a vehicle air-conditioning system of the kind mentioned above, the left and right side outlet temperatures cannot be varied by changing the operating position of the air-mixing door when the air-mixing door has already been operated to its maximum cooling position.
In Japanese Laid-Open Patent Application No. Hei. 7-251623, the positions of left and right film type air-mixing doors can be adjusted while preventing air from passing to a heater core at times of maximum cooling in a vehicle air-conditioning system using film type air-mixing doors. As a result, it is possible to adjust left and right film-type air mixing doors to selectively direct conditioned air into left and right heater core bypass passages, respectively. Therefore, even when air is delivered into left and right ventilation paths with a single, common blower it is possible for left and right cool air flows to be varied independently.
Even though there is no specific description of a relationship between blower flow and position control of the left and right film type air-mixing doors at times of maximum cooling, certain cooling limitations are present in the above-described system. For example, when blower speed is increased to increase cool air flow on the vehicle passenger side heated by a large amount of solar radiation on, for example, a hot summer day, cool air flow also increases on the driver side not heated to the same extent as the passenger side. As a result, the driver side is excessively cooled.